Rotating light projector

ABSTRACT

A light projector for movie projectors, search lights, slide projectors, etc. is provided with a rotating high intensity bulb that increases the life of the bulb and improves the light characteristics of the light projector. The bulb is mounted in special adapters that permit a ready alignment of the bulb with a reflector while maintaining the alignment during rotation of the bulb. A solenoid activated indexer coacts with a pinion gear mounted with respect to the bulb to provide the rotation. The rotation can be continual, a step rotation or a non-uniform rotation. A pair of slip ring bushings are provided to mount the ends of the adapters with one adapter being machined to provide a profile or camming surface, particularly matched to the light spot of the bulb. The slip ring bushings further provide electrical connections for the anode and cathode members of the bulb. The pinion gear is mounted on the bulb and coacts with a ratchet pawl that is driven by a solenoid for rotating the bulb. The pinion gear can double as a director of air flow from a fan along the axial length of the bulb member for cooling purposes. Various plates and rods are arranged to provide an alignment of the bulb member with respect to the reflector through the connection of one of the mounting slip ring bushings. Appropriate circuitry is provided for rotating the bulb, for example, for initiating the rotation upon the energization of the bulb member circuit.

Uted States atent [1 1 Pichel Sept. 11, 1973 ROTATING LIGHT PROJECTOR [75] Inventor: Marlowe A. Pichel, Altadena, Calif.

[73] Assignee: Pichel Industries, Inc., Pasadena,

Calif.

[22] Filed: Apr. 14, 1972 [21] App]. No.: 244,201

3,624,386 11/1971 Plumadore 240/44.2

Primary Examiner-Samuel S. Matthews Assistant ExaminerRichard M. Sheer Attorney-Harold L. Jackson et al.

57 ABSTRACT A light projector for movie projectors, search lights, slide projectors, etc. is provided with a rotating high intensity bulb that increases the life of the bulb and improves the light characteristics of the light projector. The bulb is mounted in special adapters that permit a ready alignment of the bulb with a reflector while maintaining the alignment during rotation of the bulb. A solenoid activated indexer coacts with a pinion gear mounted with respect to the bulb to provide the rotation. The rotation can be continual, a step rotation or a non-uniform rotation. A pair of slip ring bushings are provided to mount the ends of the adapters with one adapter being machined to provide a profile or camming surface, particularly matched to the light spot of the bulb. The slip ring bushings further provide electrical connections for the anode and cathode members of the bulb. The pinion gear is mounted on the bulb and coacts with a ratchet pawl that is driven by a solenoid for rotating the bulb. The pinion gear can double as a director of air flow from a fan along the axial length of the bulb member for cooling purposes. Various plates and rods are arranged to provide an alignment of the bulb member with respect to the reflector through the connection of one of the mounting slip ring bushings. Appropriate circuitry is provided for rotating the bulb, for example, for initiating the rotation upon the energization of the bulb member circuit.

16 Claims, 4 Drawing Figures PATENIED 1 3.758.769

sum 1 or 3 PAIENIEU E 3.758.769

SHEET 2 ur 3 sum 3 or 3 ROTATING LIGHT PROJECTOR BACKGROUND OF THE INVENTION 1. Field of the invention The present invention is directed to providing an increased life for a high intensity light bulb positioned in a horizontal plane by rotating the light bulb while at the same time retaining the necessary exact alignment of the center of the light source with a reflector.

2. Description of the Prior Art The problems associated with providing a high intensity light are well known in the prior art. Initially, the prior art resorted to an arc lamp which utilized a high intensity flaming arc for projection purposes such as for spot lights and projection of motion pictures. The are lamp provided the intensity of light desired but created problems with respect to the positioning of the electrodes and the heat generated by their consumption.

The Hall U. S. Pat. No. 1,677,521 (1928) disclosed a particular embodiment of an arc lamp where the positive electrode was rotated and fed relative to an auxiliary electrode to prevent the auxiliary electrode from being damaged by the heat of the are.

A U. S. patent granted to Winston, U. S. Pat. No. 1,279,061 (1918) disclosed a conventional head light mounted within a reflector where a manual rotation would rotate an eccentric member and accordingly also rotate the hot-spot of the filament relative to the reflector itself. By this means, the hot spot of the lamp filament could be appropriately adjusted to give the best reflecting illumination from the reflector.

Recent developments in the field of lighting have created high intensity bulbs that are capable of generating a light intensity that would match that of an arc lamp without the need of consuming electrodes. These high intensity bulbs also provide the advantage of a lighter construction. The major drawback in their utilization, however, is the high cost of these bulbs such as the xenon bulb. In addition, the bulbs still generate considerable amounts of heat and require high voltages to be utilized for their operation.

As utilized in this specification, a high intensity bulb can be a mercury or xenon bulb. For example, a high intensity per unit volume 2,500 watt xenon bulb produces 100,000 lumens with a voltage of 28 volt s and a current flow of 90 amps. The length of the bulb is approximately 11 inches with a glass envelope of 2.4 inches and an arc length of 0.28 inches having an average are brightness of 61,000 candles/cm.

A high intensity bulb such as the xenon bulb consists of a cathode and an anode axially aligned within a hand blown glass envelope. The interior of the bulb is filled with a gas such as xenon. The initial application of these bulbsconsisted of arranging the bulb along a vertical axis with the light being projected from a hot spot or light source that would be generated between the cathode and the anode approximately on the axial vertical axis. During the operation of the bulb, gaseous metal from principally the anode would be generated and due to convection forces of the gas within the bulb member, would be deposited adjacent the base of the anode. The depositing of this material adjacent the base of the anode would not create any problems with respect to the transmission of light through the glass envelope since it would generally be-out of the transmission band of useful light, and further any heat problems associated with the depositing would also be minimized by its location adjacent the base which would form a heat sink and help transmit the heat from the gas. During the operation of the bulb, the pressure within the envelope rises to an explosive degree due to the heat generated.

Recently in an attempt to more fully utilize the full 360 degree band of transmission light that is generated from the are light source or hot spot between the anode and cathode, high intensity bulbs such as the xenon bulb have been placed in a horizontal plane with a reflector arranged to transmit light parallel to the axial length of the bulb. Commercial embodiments of this horizontal high intensity bulb have been utilized, how ever, it has been found that the positioning of these bulbs in a horizontal plane will shorten the life of the bulb by as much as 50 percent. This is a considerable drawback considering the relatively high cost of the high intensity bulb. It has also been found that the high intensity bulbs when placed in a horizontal plane are more prone to provide heat stress to the glass envelope than when in the vertical plane. The anode material that has been gasified or reduced to extremely small SUMMARY'OF" THE INVENTION The present invention permits a high intensity light bulb such as an xenon bulb to be utilized in a horizontal plane for the total life characteristic of the bulb. This is accomplished by the rotation of the bulb to prevent the formation of a black spot which would ultimately reach a degree that would create a black band in the reflection of the light from, for example, a reflector onto a screen. By rotating the bulb, the anode material would be deposited about the full 360 degree inner circumference of the gas envelope and the actual bulb life would expire before the amount of deposited material could affect the optical illumination characteristics of the bulb. In addition, the formation of a localized hot spot which is created when the material accumulates at any one point will be eliminated with the resultant elimination of heat stresses on the glass envelope. Thus, the prospects of an explosive cracking of the bulb will be minimized by the present invention. Finally, the present invention permits the maintaining of the critical alignment of the hot spot or center of the are light source relative to the reflector during the rotation thus permitting the rotation of the bulb and its increased life expectancy to be a realistic possibility.

During the manufacturing of a high intensity light bulb such as an xenon bulb the axial alignment of the anode and cathode relative to the anode terminal and the cathode terminal of the bulb are frequently one eighth inch misaligned. Numerous problems are associated with the alignment of these members and the bulb cost would be increased considerably if a close tolerance was required. With a one eighth of an inch misalignment between the ends of the light bulb and the center of the are light source between the anode and the cathode, a rotation of the bulb would produce a cyclic error in alignment relative to the reflector. De-

pending upon the particular use of the light source, it is quite common to require a plus or minus 0.005 inch alignment between, for example, a reflector and a high intensity are light source. Thus an error of one eighth of an inch in rotation would produce a drastic magnification of error in reflection on, for example, a reflector. Because of the misalignment that is a characteristic of high intensity light bulbs, a simple rotation of the bulb relative to the reflector will adversely affect the projecting characteristics of the reflector and would require continual alignment of the system. By the provision of special adapters at each end of the light bulb, the present invention permits the light bulb to be aligned relative to the reflector and then maintains this alignment even though the high intensity light bulb is rotated to increase its life. This is accomplished by providing a cammed aspherical adapter having a camming profile designed to nullify the misaligning effects that are intrinsic in a high intensity light bulb. The cam adapter is machined relative to the specific misalignment of a particular bulb and accordingly maintains a correct alignment as the bulb is rotated.

1 In addition, mounted adjacent the aspherical adapter is a combination pinion member and heat sink which acts to dissipate the heat that accummulates on the anode side of the bulb. A solenoid or an electrical motor can be provided for rotating the pinion gear with appropriate circuitry for the desired degree of rotation or form of rotation. For example, a solenoid could utilize a ratchet for step rotation or a continual rotation or a non-uniform continual rotation. In one advantageous embodiment, the solenoid could be connected to the operating energization switch for the bulb so that the bulb will be rotated upon energization of the circuit during an initial start up of the light projector and thereby permit the rotation'of the bulb before igniting the bulb and while the bulb is still cold. A rotation before the igniting of the bulb is also advantageous since it would prevent any arcing contacts from being created.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of the present invention;

FIG. 2 is an end view of the calibrating plates of the present invention;

FIG. 3 is a cross sectional end view of the means to rotate the bulb of the present invention; and

FIG. 4 is a block diagram of the electrical circuit of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As can be seen from FIG. 1, the light projector 2 of the present invention comprises a base member 4 which mounts a front support 6. Generally a case will enclose the entire structure but for purposes of the present invention it is not disclosed in the drawings. A reflector 8, for example an elliptical reflector, is mounted on the front support by appropriate bolts or other fastening devices. In the alternative, the reflector can be mounted for either manual or automatic alignment relative to a high intensity bulb 14, for example,

a xenon bulb. A number of arms 10 which in the preferred embodiment consist of an equilateral arrangement of three arms extend from the front support 6 and terminate in slip rings 12 for supporting one end of the high intensity bulb 14. The slip rings 12 can provide an electrical connection besides maintaining the mounting alignment of the high intensity bulb 14. Generally the arms 10 will be much wider than they arethick relative to the axial horizontal alignment of the high intensity light bulb 14 to provide the maximum strength with the minimum interference with the transmission of light rays from the reflector 8. Appropriate fastening means such as bolts 13 can be utilized to mount the arms 10 onto the front support 6.

As an alternative, it should be noted that the front support 6 can be fastened to the base member 4 in such a manner that it can permit a pivoting of the reflector 8 and front support 6 out of the casing of the lamp projector 2 thus facilitating the replacement of the bulb 14. For example, the lamp projector could rotate about a pivot mounting 15 when the front end is released.

A cylindrical adapter member 16 is mounted onto the cathode terminal 30 of the high intensity light bulb 14. The cylindrical adapter member 16 is in turn positioned within the slip rings 12.

A high intensity light bulb 14 such as an xenon bulb basically consists of an anode l8 and a cathode 20 with a glass envelope 22 that is conventionally hand blown and encloses a gas 24, such as xenon or mercury. It is also known to carbon mold the glass envelope but the conventional commercial bulbs are generally hand blown. The glass envelope 22 is affixed to an anode terminal 28 and a cathode terminal 30. As can be seen from FIG. 1, when the high intensity light bulb 14 is positioned in the horizontal plane, the are light source 26 will be somewhat above the axial horizontal alignment of the anode and cathode. It is common to find a misalignment of one eighth of an inch between the terminals 28 and 30 and the axis of the anode l8 and cathode 20. In a stationary bulb arrangement, this misalignment of one eighth of an inch is simply calibrated out by a relative adjustment of either the high intensity light bulb 14 or the relfector 8. The advantage of the horizontal arrangement is that a total 360 degree utilization of light transmitted can be controlled in a desired manner. However, with the horizontal alignment, anode material will be gasified and ultimately deposited as a result of the convection forces of the inert gas 24 on the top surface of the gas envelope and will further create a localized hot spot that will increase in intensity as additional material is deposited. This will ultimately shorten the useful life of the high intensity light bulb 14 by as much as approximately 50 percent or permit only one thousand useful hours of a conventional two thousand hour high intensity light bulb.

Due to the flow of the ions of gas from the cathode 20 to the anode 18, there is also a considerable amount of heat transmitted to the anode 18 that passes on to the anode terminal 28. A pinion gear member 36 having exaggerated teeth or in effect, fin-like heat transmitting members is attached adjacent and in fact over a portion of the anode terminal 28. The heat can be dissipated through this pinion gear member 36 which serves a dual function of being a heat sink and also permitting the rotation of the high intensity light bulb 14. A plenum chamber 40 is mounted onto the base member 4 and encloses the pinion gear member'36 and terminates at the top with a fan 38 which, for example, can be a 48 CFM blower. The fins or teeth members 37 of the pinion gear member 36 can be optimally arranged, for example, in a helical configuration for the circulation of the air along the axial length of the high intensity bulb 14 to cool both the high intensity bulb l4 and the reflector 8.

Mounted within the plenum chamber 40 is a pawl 42 that is spring biased to contact the fins or teeth 37 for the rotation of the pinion gear 36 and consequentially the high intensity light bulb 14. A link member 44 supports the pawl 42 and is adjustably connected at one end to a spring 46 that is attached to the wall of the plenum chamber 40 and at the other end to a solenoid 48 for activation of the pawl 42.

Since it is critical that the location of the are light source 26 remain in a high degree of alignment relative to the reflector 8 even though each individual glass blown high intensity bulb 14 may have variations in alignment of the anode l8 and cathode by as much as an eighth of an inch, there is provided a cam adapter 32 having a profile or camming surface that compensates for the misalignment between the anode l8 and the cathode 20. It is highly desirable that the focal point of the reflector 8 be coincidental with the high intensity light source point 26 to maximize the transmission of light. While numerous machining methods may be utilized, it has been found that a blank cylindrical adapter that is attached to the anode terminal 28 can be appropriately machined while rotated with a concurrent observation through a microscope of the desired alignment position of the anode l8 and the cathode 20 thereby producing the desired results. The cathode 20 tip is the critical point to observe in maintaining the alignment. Ultimately, the cam adapter 32 is bevelled about the profile surface to produce a rough approximation of a ball joint thereby being advantageously designed to permit the transmission of three dimensional adjustments for the static alignment of the arc light source 26 of the high intensity light bulb 14 relative to the reflector 8. As noted above, as an alternative embodiment, the reflector 8 can be mounted for relative movement to the high intensity light bulb 14.

A slip ring bushing 34 having, for example, four fingers arranged in a spherical configuration to complement the ball shaped cam adapter 32 is provided to serve the dual function of transmitting an electrical contact for the high intensity light bulb l4 and providing a camming mounting surface for rotation. A first plate 52 is mounted on the outside of the plenum chamber 40 for pennitting alignment in the X direction which is transmitted to the slip ring bushing 34 through a sleeve member 53. Likewise, a second plate 54 transmits motion along the Y axis in a similar manner. Finally, a threaded rod 56 terminating in a gnarled handle member 58 is capable of transmitting axial motion along the Z plane. This alignment motion is transmitted to the high intensity light bulb 14 to provide the correct positioning of the are light source 26 relative to the reflector 8. As the high intensity light bulb 14 rotates in the horizontal plane, the convection currents will maintain the are light source 26 above the horizontal axial axis of the anode l8 and the cathode 20.

The rotation of the high intensity light bulb 14 can be accomplished in a step function, a continual rotation, or even a non-uniform rotation. In the preferred embodiment, the rotation is initiated and performed before the bulb is ignited thereby removing any problem of arcing due to a sliding contact and also providing a rotation of the bulb while it is still in a cool and relatively safer condition. This initial rotation can be accomplished as seen in FIG. 4 where a power supply 62 is connected to an on-off mechanical switch 64. A high voltage igniter circuit 66 which can be seen in more detail in the allowed patent application Ser. No. 833,962 filed on May 8, 1969 is connected to the lamp bulb 68 to provide the initial high voltage for igniting the lamp bulb arc. A constant running DC. voltage source 70 is monitored by a sensor 72 which can disconnect both the igniter circuit 66 and the rotating motor 74. A switch 76 can be mechanically controlled by the motor 74 whereby the motor 74 will be energized to rotate the lamp bulb 68 before application of the high voltage to the lamp bulb 68.

It should be noted that various modifications can be made to the apparatus while still remaining within the purview of the'following claims.

What is claimed is:

1. A high intensity light projector comprising:

a base member lying in a horizontal plane;

support means vertically mounted on the base member;

electrical connectors adapted to be energized by electrical power;

a high intensity light bulb having spaced apart electrodes horizontally mounted on the support means and connected to the electrical connectors such that the electrodes are substantially aligned in a horizontal plane and a high intensity light source point is created between the electrodes;

a reflector having a predetermined focal point mounted about the high intensity light bulb with its focal point coinciding with the high intensity light source point;

means for rotating the high intensity light bulb to increase the operative life of the high intensity light bulb; and

mechanical means for maintaining the coincidental alignment of the high intensity light source point and the focal point of the reflector as the high intensity light bulb is rotated.

2. A high intensity light projector as in claim 1 where the mechanical means for maintaining alignment includes a cam adapter mounted at one end of the high intensity light bulb and having a camming profile which compensates for any misalignment of the high intensity light source point and focal point which would occur upon rotation.

3. A high intensity light projector as in claim 1 where the means for rotating includes a pinion gear mounted at one end of the high intensity bulb and a motor means for operatively contacting the pinion gear.

4. A high intensity light projector as in claim 3 further including a plenum chamber surrounding the pinion gear and a source of compressed air connected to the chamber.

5. A high intensity light projector as in claim 4 where the pinion gear is also a heat sink and has fin like projecting teeth for transmitting heat from the high intensity light bulb to the air.

6. A high intensity light projector as in claim where the fin like projecting teeth are helical to direct the air in an axial horizontal direction along the high intensity light bulb.

7. A high intensity light projector as in claim 2 where the support means further includes a slip ring bushing which provides a camming follower for the cam adapter.

8. A high intensity light projector as in claim 7 where the slip ring provides an electrical connection to the high intensity light bulb.

9. A high intensity light projector as in claim 7 further including means for aligning the reflector and high intensity light bulb.

10. A high intensity light projector as in claim 9 where the alignment motion is transmitted to the high intensity light projector through the slip ring bushing and the cam adapter.

11. A high intensity light projector as in claim 3 where the motor means is a solenoid and pawl.

12. A high intensity light projector as in claim 3 further including a switch for energizing the high intensity light bulb and means for first energizing the motor means to rotate the high intensity light bulb'before energizing the light bulb.

13. A high intensity light projector as in claim 3 where the support means can pivot about one end relative to the base member to permit the reflector and high intensity light bulb to be moved as a unit.

14. A high intensity light projector comprising:

a base member lying in a horizontal plane;

support means vertically mounted on the base member;

electrical connectors adapted to be energized by electrical power;

a high intensity light bulb having spaced apart electrodes horizontally mounted on the support means and connected to the electrical connectors such that its electrodes are substantially aligned in a horizontal plane and a high intensity light source point can be created between the electrodes;

a reflector having a predetermined focal point mounted about the high intensity light bulb with its focal point coinciding with the high intensity light source point;

means for rotating the high intensity light bulb to increase the operative life of the high intensity light bulb;

means for maintaining the coincidental alignment of the high intensity light source point and the focal point of the reflector as the high intensity light bulb is rotated; and

circuit means for actuating the rotation of the high intensity light bulb before the electrical connectors are activated with electrical power to create the high intensity light source point.

15. An illuminating device reflecting light emitted by an arc source which comprises:

an arc lamp having a central envelope portion and a pair of legs extending in opposite directions along a substantially longitudinal axis thereof with each of the legs including an electrode arranged in spaced apart relationship in the central portionof the envelope to provide an electric arc;

a reflector having a focal point and being positioned with respect to the arc lamp so that the focal point is within the electric arc;

means adapted to receive electrical power to and from said electrodes; and

mechanical rotating means connected to the arc lamp for simultaneously rotating and maintaining the electric arc at the focal point of the reflector during rotational revolutions of the arc lamp.

16. A high intensity light projector comprising:

a base member lying in a horizontal plane;

support means vertically mounted on the base member;

electrical connectors adapted to be energized by electrical power;

a high intensity light bulb having spaced apart electrodes horizontally mounted on the support means and connected to the electrical connectors such that the electrodes aresubstantially aligned in a horizontal plane and a high intensity light source point can be created between the electrodes;

a reflector having a predetermined focal point mounted about the high intensity light bulb with its focal point coinciding with the high intensity light source point;

means for rotating the high intensity light bulb to increase the operative life of the high intensity light bulb; and

means for maintaining the coincidental alignment of the high intensity light source point and the focal point of the reflector as the high intensity light bulb is rotated including a camming profile which compensates for any misalignment of the high intensity light source point and focal point which would occur upon rotation.

t l t 

1. A high intensity light projector comprising: a base member lying in a horizontal plane; support means vertically mounted on the base member; electrical connectors adapted to be energized by electrical power; a high intensity light bulb having spaced apart electrodes horizontally mounted on the support means and connected to the electrical connectors such that the electrodes are substantially aligned in a horizontal plane and a high intensity light source point is created between the electrodes; a reflector having a predetermined focal point mounted about the high intensity light bulb with its focal point coinciding with the high intensity light source point; means for rotating the high intensity light bulb to increase the operative life of the high intensity light bulb; and mechanical means for maintaining the coincidental alignment of the high intensity light source point and the focal point of the reflector as the high intensity light bulb is rotated.
 2. A high intensity light projector as in claim 1 where the mechanical means for maintaining alignment includes a cam adapter mounted at one end of the high intensity light bulb and having a camming profile which compensates for any misalignment of the high intensity light source point and focal point which would occur upon rotation.
 3. A high intensity light projector as in claim 1 where the means for rotating includes a pinion gear mounted at one end of the high intensity bulb and a motor means for operatively contacting the pinion gear.
 4. A high intensity light projector as in claim 3 further including a plenum chamber surrounding the pinion gear and a source of compressed air connected to the chamber.
 5. A high intensity light projector as in claim 4 where the pinion gear is also a heat sink and has fin like projecting teeth for transmitting heat from the high intensity light bulb to the air.
 6. A high intensity light projector as in claim 5 where the fin like projecting teeth are helical to direct the air in an axial horizontal direction along the high intensity light bulb.
 7. A high intensity light projector as in claim 2 where the support means further includes a slip ring bushing which provides a camming follower for the cam adapter.
 8. A high intensity light projector as in claim 7 where the slip ring provides an electrical connection to the high intensity light bulb.
 9. A high intensity light projector as in claim 7 further including means for aligning the reflector and high intensity light bulb.
 10. A high intensity light projector as in claim 9 where the alignment motion is transmitted to the high intensity light projector through the slip ring bushing and the cam adapter.
 11. A high intensity light projector as in claim 3 where the motor means is a solenoid and pawl.
 12. A high intensity light projector as in claim 3 further including a switch for energizing the high intensity light bulb and means for first energizing the motor means to rotate the high intensity light bulb before energizing the light bulb.
 13. A high intensity light projector as in claim 3 where the support means can pivot about one end relative to the base member to permit the reflector and high intensity light bulb to be moved as a unit.
 14. A high intensity light projector comprising: a base member lying in a horizontal plane; support means vertically mounted on the base member; electrical connectors adapted to be energized by electrical power; a high intensity light bulb having spaced apart electrodes horizontally mounted on the support means and connected to the electrical connectors such that its electrodes are substantially aligned in a horizontal plane and a high intensity light source point can be created between the electrodes; a reflector having a predetermined focal point mounted about the high intensity light bulb with its focal point coinciding with the high intensity light source point; means for rotating the high intensity light bulb to increase the operative life of the high intensity light bulb; means for maintaining the coincidental alignment of the high intensity light source point and the focal point of the reflector as the high intensity light bulb is rotated; and circuit means for actuating the rotation of the high intensity light bulb before the electrical connectors are activated with electrical power to create the high intensity light source point.
 15. An illuminating device reflecting light emitted by an arc source which comprises: an arc lamp having a central envelope portion and a pair of legs extending in opposite directions along a substantially longitudinal axis thereof with each of the legs including an electrode arranged in spaced apart relationship in the central portion of the envelope to provide an electric arc; a reflector having a focal point and being positioned with respect to the arc lamp so that the focal point is within the electric arc; means adapted to receive electrical power to and from said electrodes; and mechanical rotating means connected to the arc lamp for simultaneously rotating and maintaining the electric arc at the focal point of the reflector during rotational revolutions of the arc lamp.
 16. A high intensity light projector comprising: a base member lying in a horizontal plane; support means vertically mounted on the base member; electrical connectors adapted to be energized by electrical power; a high intensity light bulb having spaced apart electrodes horizontally mounted on the support means and connected to the electrical connectors such that the electrodes are substantially aligned in a horizontal plane and a high intensity light source point can be created between the electrodes; a reflector having a predetermined focal point mounted about the high intensity light bulb with its focal point coinciding with the high intensity light source point; means for rotating the high intensity light bulb to increase the operative life of the high intensity light bulb; and means for maintaining the coincidental alignment of the high intensity light source point and the focal point of the reflector as the high intensity light bulb is rotated including a camming profile which compensates for any misalignment of the high intensity light source point and focal point which would occur upon rotation. 